In my working field we have large pdf reports and powerpoint presentations. So on my forum I want users to be able to upload large files (max filesize = 64 mb). I've uploaded a .htaccess file to the server with php_value upload_max_filesize 64M Also I changed the Xenforo options to 65536 KB, maximum attachment size First I could upload 2 MB-files, after the changes I now can upload 8 MB-files When I upload a 16 MB file, I get the following error : Security error occurred. Please press back, refresh the page, and try again. The error doesn't give much info. Is this an Xenforo error, or has it to do with my hosting company ? Thanks in advance.